1. Field of the Invention
The present invention relates to a method of adjusting conditions for recording and reproducing optical informations into and from an optical information storage medium as well as an apparatus for recording and reproducing optical informations.
All of patents, patent applications, patent publications, scientific articles and the like, which will hereinafter be cited or identified in the present application, will, hereby, be incorporated by references in their entirety in order to describe more fully the state of the art, to which the present invention pertains.
2. Description of the Related Art
A variety of optical disk is one of typical examples of optical information storage mediums for storing informations. The optical disk may, for example, include DVD-R, DVD-RW and DVD+RW, which have been developed, and some of which have been commercially available. The optical disk stores various informations by utilizing a multi-pulse method, wherein a set of plural laser pulse is used for storing one mark onto the disk. FIG. 1A is a schematic view illustrative of a set of plural laser pulses used for storing one mark onto a DVD-R in the prior art. FIG. 1B is a schematic view illustrative of a set of plural laser pulses used for storing one mark onto a DVD-RW in the prior art. FIG. 1C is a schematic view illustrative of a set of plural laser pulses used for storing one mark onto a DVD+RW in the prior art. In the multi-pulse methods shown in FIGS. 1A, 1B and 1C, a 6T-signal, which means a mark with a length “6T” being six times of a channel clock cycle “T”, is used for record so called as record strategy. A width of the each laser pulse generally depends on the kind of the optical disk and a maker. There are different regulations for each laser pulse, depending upon the kinds of the optical disk. Informations of the regulations such as a laser pulse width adjusted to the disk are written into the disk in the maker side. In FIGS. 1A, 1B and 1C, “Pw” represents a record power level, “Pe” represents an erase power level, and “Pb” represents a bottom power level. “Tcl” represents a cycle which represents a time period of the bottom power level “Pb” appearing after a last pulse included in the set of plural laser pulses. “Ttop” represents a pulse width of a top pulse included in the set of plural laser pulses. “Tmp” also represents a pulse width of remaining pulses subsequent to the top pulse included in the set of plural laser pulses. Usually, adjustments to the above parameters are made to minimize a fluctuation or a jitter.
In the cases shown in FIGS. 1A, 1B and 1C, the remaining pulses subsequent to the top pulse have a uniform pulse width “Tmp”, for which reason the remaining pulses subsequent to the top pulse are uniformly adjusted in pulse width “Tmp”. In rear case, it may be possible that the last pulse has a specific pulse width which is different from the uniform pulse width “Tmp” of the remaining pulses subsequent to the top pulse and prior to the last pulse.
Each of the above described optical disks has an area in which a recommend record strategy is buried for allowing adjustment to the record power. There are two methods for adjustment to the record power. One of a β-method, wherein an asymmetry of long and short marks is checked to find a β-value. Another is a γ-method, wherein the need for the adjustment is decided depending upon a degree of saturation of amplitude of the record mark. Generally, the β-method is used for DVD-R, while the γ-method is used for DVD-RW, DVD+RW. The record strategy relies upon only the informations buried in the disk.
Japanese laid-open patent publication No. 2000-182244 discloses a first conventional method of adjusting the record strategy, wherein some power levels are assigned to parameters for the record power and the record strategy so that tests in cases of all combinations are comprehensively made to select an optimum combination of the levels.
Japanese laid-open patent publication No. 2000-30254 discloses a second conventional method of adjusting the record strategy, wherein an adjustment to the record strategy and another adjustment to the record power are made separately from each other, and the record power level is decided depending on the length of the mark.
Japanese laid-open patent publication No. 2001-155340 discloses a third conventional recording method under a simple control, which is available to CAV, ZCAV, or CLV at any speeds. The method is to form recording marks over an optical storage medium with variable record line speeds in accordance with the multi-pulse method, wherein a laser pulse emission pattern and a pulse length are optimized at the highest one of available record line speeds. In accordance with the kind of pulse, the record power is assigned to a series of plural laser pulses for forming the record mark, wherein at least two different record power levels are included in the series of the plural laser pulses. Each of the different record power levels is controlled in accordance with either the record line speed or a record position over the optical storage medium. The control of the record power in accordance with the record line speed or the record position allows the recording with a low fluctuation or a low jitter in the range of practical line speed even the length of the emitted pulse of the record strategy is fixed constant.
In general, however, the optimum record strategy is slightly variable depending on a state of an optical head, and a setting of a driver circuit, for which reason it is preferable to adjust the record strategy obtained from the disk with reference to a driver.
The above-described conventional techniques have the following problems and disadvantages.
The first conventional method making a large number of the tests is not suitable for a desired quick adjustment.
The third conventional method making the setting of the recording strategy responsible to any recording line speed and any recording positions need to measure the fluctuation or the jitter and further measure the length of the mark, for which reason the third conventional method not suitable for the desired quick adjustment.
Further, the second conventional method making separate adjustment processes for the recording strategy and the parameters is also not suitable for the desired quick adjustment.
The above first to third conventional methods are not efficient adjustment methods for adjusting the recording strategy.
In addition, accomplishment of a large number of the tests need a large specific area for adjustments. Particularly if the disk is a medium allowing one-time writing such as DVD-R, then the limited specific area for adjustment may be insufficient.
In the first conventional method, practically, the first adjustment needs to carry out 63 tests, and further the second adjustment also needs to carry out 27 tests, and in total, the completion of the adjustment needs 90 tests which comprises the 63 tests and the 27 tests. For which reason, a large specific area of the disk is needed for adjustment for wiring or recording information onto the disk. The need of the large specific area for adjustment means that re-write operation and/or additional write operation makes the limited specific area for adjustment insufficient. Namely, there is a limitation of the number of available re-writing operations.
In the above circumstances, the development of a novel method of adjusting conditions for recording informations onto an information storage medium free from the above problems is desirable.